1. Field of the Invention
The present invention relates to an apparatus for automatically mounting tension springs (tension coil springs) to a seat frame of a vehicle seat or the like, which tension springs are used to support a pad receiving member.
2. Description of the Prior Art
Conventionally, a seat for use in a vehicle or the like includes such a cushion structure as disclosed in Japanese Utility Model Publication No. 47-5882.
In the above-mentioned cushion structure, as shown in FIG. 8, between two side portions (1a)(1b) of a seat frame (1) located within the seat, a so-called "screen-like" pad receiving member (5), which is formed by extending a plurality of wires (3) between two side members (2a)(2b) and then inserting a separation member (4) between these wires (3), is resiliently provided via a plurality of tension springs S which are positioned at the two sides of the pad receiving member (5), so that a comfortable cushioning effect can be obtained by such resilency.
Mounting of the above-mentioned tension springs S for the pad receiving member (5) in the seat frame (1) is performed almost by means of manual operations in the prior art. Also, in the prior art, to mount the tension springs to the seat frame, a required number of tension springs S are sequentially mounted to one side portion of the seat frame (1) from either of the forward or rearward portion thereof in such a manner that one of two hook portions symmetrically formed in the two ends of each of the tension springs S is engaged with a side member of the pad receiving element (5) and the other hook portion is inserted through a through-bore (6) formed in the side portion of the seat frame (1) as an engagement portion; and then, similarly, a required number of tension springs S are mounted to the other side portion of seat frame (1) as well.
In the above-mentioned conventional tension spring mounting operations, the mounting of the tension springs in the one side portion of the seat frame can be performed relatively easily, while the mounting operations of the tension springs in the other portion after the mounting operations in the above-mentioned one portion are very difficult to be carried out.
In other words, in a condition that the tension springs have been installed between the one side portion (1a) of the seat frame (1) and the one side member (2a) of the pad receiving element (5), when mounting the tension springs S in the other portion (1b) thereof, at first the other side member (2b) of the pad receiving means (5) is pulled toward the other side portion (1b) of the seat frame (1) against the biasing forces of the already-installed tension springs in the one side portion of the seat frame and then, while maintaining this tensioned state, the respective both-side hook portions of the tension springs S must be made correspond accurately to the through bores (6) of the seat frame (1) and the other side member (2b) of the pad receiver (5) for engagement therewith. Thus, this operation requires a great deal of labor and is not efficient.
To avoid the above-mentioned laborious manual operation, conventionally, there has been made a trial which uses a so-called "industrial robot" to perform the mounting operation of the tension springs S automatically. However, in the automatic tension springs mounting operation by the robot, there are many problems to be solved: for example, it is difficult to catch or grasp one tension spring to be mounted out of a great number of tension springs because the hook portions of the tension spring may be entangled with the hook portions of other tension springs to be unseparable therefrom; or, when mounting the tension springs S to their associated mount places, since it is difficult to correspond the hook portions Sa thereof to the associated through-bores (6) in the seat frame (1) correctly, the tension springs may be misplaced or misaligned.